When browsing the database list inside Microsoft SQL Server Management Studio, you may get the error below:

Failed to retrieve data for this request. (Microsoft.SqlServer.SmoEnum)

Invalid column name 'mirroring_role'.
Invalid column name 'mirroring_state'.
Invalid column name 'mirroring_state'. (.Net SqlClient Data Provider)

One of the reasons for this error is that you are trying to connect to a final version of SQL Server 9.0 (SQL Server 2005) using a beta version of SQL Server Management Studio.

To be able to connect to a final release of SQL Server 2005, you also need the final release of SQL Server Management Studio, not the beta.